"It's great that the immediate future of our coaching staff has also been secured, as Matt and Mike contribute massively to what we do as a group," Townsend, whose previous deal was until 2020, said.

"We are really looking forward to Danny joining up with us, which will enable us to seek further improvements in how we can bring the best out of our players."

Townsend had five years in charge of Glasgow Warriors, leading the Scotstoun side to the Pro12 title in 2015 before taking on the Scotland job.

His playing career took in spells at Northampton, Brive, Castres, Montpellier and Border Reivers. He represented Scotland 82 times, scoring 164 points, and won two British and Irish Lions caps.

Scotland face autumn Tests against Wales, Fiji, South Africa and Argentina later this year and open the 2019 Six Nations campaign against Italy in February.

Home and away summer Tests against France and Georgia precede the 2019 World Cup campaign, with Scotland drawn in the same group as Ireland, hosts Japan, Russia and Samoa.

"We're well aware we're entering a crucial and exciting time for this group as we continue to seek improvements across the board and target a strong autumn Test series and Six Nations before our build-up to the Rugby World Cup begins in earnest," added Townsend.